Advances in naval architecture have led to the development of a semisubmerged ship having a plurality of hulls completely disposed beneath the surface of the water in which the ship is deployed. Such vessels enjoy a dynamic pitch stability and a maneuverability superior to monohull vessels of conventional design. See U.S. Pat. Nos. 3,623,444 and 3,730,123 issued to Thomas G. Lang. One embodiment of this novel concept is illustrated in FIG. 1 and is designated as a Small Waterplane Area Twin-Hull (SWATH) ship.
Because of its superior stability and maneuverability at all speeds, the SWATH ship offers an excellent platform from which various physical measurements of the ocean environment can be carried out. The usual means for carrying out real-time marine measurements is to trail a sensor package behind the moving marine vessel by means of a negatively buoyant towline attached between the vessel and the package. In conventional such an apparatus is normally deployed by paying out the package and line over the stern of the ship and towing them behind as the vessel moves through the water.
In the case of the SWATH ship, the stern deployment technique can interfere with efficient vessel operation and pose a danger of equipment damage. The combined weight of the towed array, storage reel, and related mechanical equipment is such that if the equipment were to be located at the stern of the SWATH, rather than amidships, the vessel would become imbalanced to the detriment of its stability and maneuverability. Also, because of the horizontal stabilization member connecting the submerged hulls at the stern of the ship, and because of the propellers which protrude from the hulls, a sensor package cannot be deployed from a position amidships while the ship is moving in a forward direction without running the risk of damage to the package, towline, or ship. Hence, a novel method of instrument deployment from a SWATH ship is required which will ensure the correct launching of the package without danger of damage.